Most fertilizers comprise a mixture of ingredients which have different specific gravities, and some variation in particle size. Such blended materials are not particularly useful as fertilizers unless each component or ingredient in the blend is uniformly distributed over the area in which the agricultural crop is planted. Lack of one of the fertilizer ingredients in one part of the field, and an excess in another results in spotty yields. Uniform spreading of each fertilizer ingredient over all the crop area insures maximum possible yield from the planted area, as well as most efficient use of the fertilizer per acre planted and fertilized.
There are many and diverse forms of fertilizer spreaders. One of the current commercial models includes a large tractor mounted bulk hopper which moves at a relatively high speed across the area to be fertilized. The granular fertilizer drops down through an orifice at the rear end of the hopper and impacts against a rapidly spinning, horizontally disposed circular plate. The fertilizer is thrown out in a wide, 160.degree. arc behind the spreading vehicle. These units are designed to spread a swath up to about 60 feet wide. When using the above spreader, it is most important that the blended fertilizer comprise particles of substantially identical specific gravity. Otherwise, the heaviest components will be consistently thrown to the outer edge of the swath, and the lighter components will accumulate in a path closer to the spreader.